Mercury-tube switch



May 13, 1930.

I. E. M CABE MERCURY TUBE SWITCH Filed Jan. 23, 1928 2 Sheets-Sheet 1 IN VEN TOR. IRA E. M CABE BY 6 n ATTORNEYS.

May 13, 1930.

l. E. M CABE MERCURY TUBE SWITCH Filed Jan. 25, 1928 2 Sheets-Sheet INVENTOR. IRA a. MC CABE BYX M A TTORNEYS.

Patented May 13, 1930 UNITED STATES IRA E. MCOABE, OI CHICAGO, ILLINOIS MERCfi'RY-TUBE SWITCH Application filed January 23,1928. Serial No. 248,640.

This invention relates to improvements'in mechanism for operatin electric switches and more particularly a oat actuated mechanism for Operating electric switches.

6 It is customary to employ an electrically driven pump to fill and maintain filled fluid storage tanks for different purposes as well as to emplo electrically driven pumps to draw fluids rom storage tanks for different purposes. In the first instance it is desirable to provide an automatic switch mechanism which closes the motor circuit to the pump when the fluid, recedes below apredetermined level and to break the circuit when the fluid rises and such high level is reached, and, in the second instance, to provide an automatic switch mechanism which closes the circuit to the switch as long as the fluid is above a prer determined level and to break the circuit when 'the fluid recedes and reaches such low level.

It is an object of this invention to provide anelectric switch with an operating mechanism automatically actuated by a float to open the switch at the upward and downward limits of its travel, respectively, and to close the switch and maintain it closed during travel or movement between these two points.

While preferred forms of this invention are illustrated upon the accompanying sheets of drawing, yet it is to be understood that minor detail changes may be made without departing from the scope thereof.

In the drawings:

Figure 1 is a view in front elevation of a preferred form of float operated switch as contemplated by this invention, with the fluid tank'removed.

Figure 2 is a view in end elevation of -Figure 1. I

Figure 3 is a view in front elevation of another form 'ofthis invention, with the top of the fluid tank broken away, illustrating the. position of the parts when the float is intermediate its limits of. travel and the switch is closed.

Figure 4 is a detail view in front elevation, with parts broken away, showing the position of the parts at the upward limit of the float. Figure 5 is a view similar to Figure 4, showparticular mechanism for actuating the snap cury tube switch. The lower end of the rod ing the position of the parts at the down ward limit of the float.

Figure 6 is a detail of the float arm connection shown in transverse section.

In both forms illustrated, the switch employed is a commercial type known to the trade as a mercury tube switch and is moved from its closed to open positions continuously during operation by a snap movement forming the subject-matter of the applicants 0 prior pending application Serial No. 585,698, filed September 1, 1922, and forms no part or" this invention, inasmuch as it is a commercial article which has gone into general use. The

movement of this switch is controlled by the position of a float in the tank containing the fluid. The tank is not illustrated as it may be of any known construction and the effect of change of fluid level upon a float therein is well known.

In Figures 1 and 2, a mercury tube snap switch 1 is mounted in a cylindrical casing 2 supported upon a tubular member 3 upon a hollow rod or pipe 4 adapted to pass through and extend beyond the top of a fluid tank, not

shown, and be secured thereto by a screw threaded block 5, surrounding and secured to the pipe, engaging in similarly screw threaded opening in the top of the tank and support the switch casing thereabove, The lower end of the pipe 1 is closed by a hollow plug 6, secured in any desired manner thereto, which acts as a guide for the lower end f of an actuating rod 7 which passes therethrough, through the pipe 4 and tubular member 3 into the casing 2 and is pivotally attached at its upper end to the actuating member 8 of the snap movement of the mer- 7 is pivotally attached to a float arm 9, of a construction hereinafter to be described, in

. such a manner as to draw the actuating rod downward through the guide 6 as the float arm 9 travels in an upward or downward rotation about its pivotal connection and, at the limits of rotation of the float arm in both directions, the movement of the rod 7 imparts a downward movement to theactuating member 8 of the snap movement of the switch to snap the mercury tube into open position, yet movement of the float arm 9 between its upward and downward limits imparts an upward movement to the rod 7 and likewise to the member 8 to snap the switch into its closed position, as hereinafter described.

Figure 3 illustrates the switch 1 and its operating mechanism supported upon a plate 10 adapted to beinserted through an opening 11 in the top wall 12 of a fluid tank which plate is carried on the under side of a closure 13 secured in any desired manner to the tank wall about the opening 11 with only the bind-- ing posts 14 and switch reset 15 extending above the tank wall. In this form, the guide block 6 is carried upon the lower end of the plate 10 which I supports or mounts the mercury tube switch and its actuating mechanism all within the interior of the tank.

The operation of the float actuated mechanism is thesame in both forms. Figure 3 shows the parts when the float is intermediate its limits of movement and the circuit closed through the switch. Figure 4 shows the position of the float arm 9 when the float has reached its upward limit, and Figure 5 when the float has reached its downward limit, with the switchin both cases in open position with the circuit broken therethrough. The float 16 is not shown in connection with these figures as it is shown in Figures 1 and 2 in the normal or intermediate position in full lines and at its limits of travel in dotted lines with the correspondingpositions 'of the float arm 9 shown in full lines on Figures 3, 4, and 5, in' the normal, up limit and down limit positions, respectively.

While'the mechanism for imparting a snap movement to the mercury tube switch in opening and closing the circuit in which it is included is the subject-matter of the applicants above referred to prior pending application, a brief explanation thereof is necessary to'the full understanding of the manner it is operated by the movement of the float as contemplated by this invention. The mercury tube switch 1 comprises a seal-ed tube into which project spaced apart terminals adjacent one end and a sufficient amount ofv mercury to flow from end to end as the switch tube is tilted, and in one position to contact both terminals to close the circuit therethrough and when flowing to the opposite end to break the connection between said terminals. The terminals are connected by flexible leads 17 through the condulet box 2 shown at the rear of the casing 2, Figure 2, or to the binding posts 14, shown in Figure 8, to be connected in turn to the circuit to be controlled. The mercury tube is supported in clips 18 depending from an angular extension 19 at the top of the pivoted. supporting plate 20 which is provided at its left-hand edge with two joined and oppositely extending angular surfaces 21 and 22 and its opposite edge with a cutaway surface providing a space between two outwardly extending arms 23 adapted to engage a fixed stud 24 to limit the rotative movement in both directions about itspivot. An actuating member 8 in the form of a plate is pivotally mounted below the tube supporting plate 20 having extensions on opposite sides adapted to engage fixed studs 25 and 26 to limit its rotative movement in both directions. An actuating link 27 is pivotally mounted at the end to the left of the pivotal point of the actuating member, the other end of said link mounting a roller 28 adapted to engage and roll over the angular faces 21 and 22 of the supporting plate and is held with the roller in engagement therewith by a spring 29 secured to the link midway between the roller and pivotal engagement to the actuating member with the other end of the spring secured to the fixed post 26.

The float operated actuating rod 7 is pivotally engaged at its upper end with the switch actuating member 8 to the left of its pivot 80 and the actuating rod 7 is normally held at the upward limit of its travel by a spring 38 either engaging a shoulder upon said arm and resting on the bottom of the casing 2, as shown in Figure 1, or resting upon the guide '6, as shown in Figure 3. When the actuating rod 7 moves upward to the limit of its movement in that direction it causes the left-hand portion of the actuating member 8 to swing upward about its pivot 30 which imparts an upward movement of the actuating link causing the roller 28 carried on its upper end to travel over and engage the upper angular face 21 of the supporting plate 20 causing the plate to rotate in that direction until the arm 23 thereof engages the fixed stud 24. In this position the mercury has flowed into the end containing the two terminals and the circuit is closed. From the above description it is readily seen that when the actuating rod 7 is drawn downward from the position shown in Figure 3, the roller 28 is moved downward and travels over the angular surface 21 until it rides over the apex and as soon as it engages the lower angular surface 22, the tension of the spring 29 causes the rollor 28 not only to ride over the surface 22 but at the same time to snap the supporting plate about its pivot until its upper extending arm 23 engages the fixed stop 24, as shown in Figures 4 and 5, whereby the mercury tube is tilted to open position.

It has been said that the end of the float arm 9 pivoted to the lower end of the actuatend of the rod 7 passes through and is guided by block 6. The block 6 is slotted as shown in all'of the figures, the body of the block above the upper end of the slot forming shoulders 31 and 32 on opposite sides of the rod 7..

The lower end of the rod 7 is also slotted with the slot 33 therein normally extending above the opposite shoulders 31 and 32 closing the slot in the block 6. The float arm 9 is secured to the float 16 at one end and the other end is passed through the slots in the guide block 6 and actuating rod 7 and after projecting beyond the opposite side of the guide block 6 is pivoted adjacent its upper edge by a pin 34 passing through the opposite sides of the slotted end of the actuating rod 7. The upper edge of the float arm 9 is cut away in the form of a semi-circle about the pivotal point leaving sufiicient metal to support the arm 9 upon the pivot 34. Referring to Figures 3, 4, and 5, the body of the arm 9 to the left of the semi-circular body surrounding the pivot 34 is cut away for a short distance at an angle inclining in the direction of the corner formed at the end of the arm 9 and the lower edge, then the upper surface is cut away at a decided angle toward the lower edge forming a shoulder 35 adapted to engage the shoulder 31 of the guide block slot. The body of the arm'9 to the right of the semi-circular body surrounding the pivot 34 is cut away at an angle inclining in the direction of the upper edge of the arm 9 to the right and then at a decided angle downward therefrom in the direction of the lower edge and then the cut extends upward to the upper edge of the arm 9, forming a shoulder 36 adapted to engage the shoulder 32 of the guide block slot with the reentrant angular cut-out port-ion 37 being of suflicient depth and Width to allow the upper edge of the arm 9 to clear the guide block when the shoulder 36 engages the shoulder 32 thereof.

The shoulders 35 and 36 are so formed that when the float 16 is midway between its upper and lower limits of travel both shoulders 35 and 36 will engage both shoulders 31 and 32 of the guide block 6 allowing the spring 38 acting upon the actuating rod 7 to expand and force the rod upward, drawing the semicircular body surrounding the pivot 9 of the float arm within the guide block above the shoulders 31 and 32 thereof, as shown in Figure 3. The upper end of the actuating rod 7 is so pivoted to the actuating member 8 that when the rod has reachedthe end of its upward movement the actuating member 8 has completed its rotation to close the switch, as shown in Figure 3. As seen in Figure 3, the actuating member may be rotated in a downward direction and likewise the actuating rod 7 may be moved in a downward direction the distance the roller 28 moves in traveling over the angular surface 21 to its apex without changing the relation of the switch tube. As

the level of the fluid in the tank rises the float is caused to travel upward causing the float arm 9 to fulcrum on its shoulder 36 in engagement with shoulder 32 of the guide-block 6 and through pivot 34 draw the actuating arm 7 in a downward direction compressing the spring 38 until the roller 28 passes over the apex and engages the under side 22 of the tube supporting plate 20 whereupon the mercury tube is snapped intothe open position, as shown in Figure 4. As the level of the fluid in the tank decreases the float travels downward, whereupon the spring 38 causes the pivot pin 34 to be drawn upward and the parts assume the position shown in Figure 3 with the switchclosed. Upon continued decrease in the level of the fluid in the tank, the float continues to travel downward causing the shoulder 35 of the float arm to engage the shoulder 31 of the guide block and then causes the float arm to fulcrum on this point of contact and draw the actuating arm downward against the tension of the spring 38 until the roller 28 engages the under surface 22 of the tube supporting plate 20 and causes the parts to assume the position shown in Figure 5 with the switch in open position. As the float travels upward the switch is again closed as above described.

The operation just described is that employed when it is desired to utilize a motor driven pump to fill and maintain a tank full of a desired fluid and the parts are so constructed that when the tank is empty the float cannot rest upon the bottom of the tank when the switch is closed. In order to over come the weight of the float in the initial filling of the tank, a means is provided for moving the actuating member 8 of the switch mechanism to close the switch. As shown in Figure 1, the portion to the right of the pivot 30 of the actuating member 8 is provided with a curved depending projection 39 with a pin 3.) adapted to be engaged by a lug 4O rotatably mounted upon the rear of the casing 2 adapted to be manually rotated by the knurled knob 41 upon the exterior thereof so that the lug 40 will engage the depending pin 39 and cause the member 8 to be rotated about its pivot to close the switch, and in Figure 3, the angular part 19 of the supportingplate 20 is provided with an extension 42 having a sliding connection with a shaft 43 extending upward through closure plate 13 and terminating thereabove in a knurled re set handle 15. The lower end of the shaft is adapted to engage the under side of the ex tension 42 whereby the shaft 43 may be manually drawn upward to close the switch. After the fluid in the tank rises to a point Where the float normally closes the switch, the manual operation thereof is discontinued and thereafter when the level has risen to the desired height, the float causes the mechanism controlled thereby to open the switch,

then when the level lowers the switch is closed until the desired level is again reached, thereby automatically maintaining the tank filled. Of course, it is to be understood, that adjustments may be made to accommodate the levels desired between which the switch is to be closed and opened.

Should the float l6 fail to operate, as is often the case after long usage, leak or become punctured by action of the fluid therein, it will sink through the fluid to the lower limit of its travel and open the switch so that it'acts as a safety device whereby the tank cannot be again automatically con trolled until the damaged float is replaced or repaired.

While the float arm 9 may be made in one piece extending from its pivotal connection to the actuating rod 7 to the float, it is preterable to make it in two pieces, as shown in Figures 1 and 2, having overlapping ends 44 and 45 with corresponding angular depressions, as shown in Figure 6, held together by a pin 46 and spring 47 thereon, whereby, when handling or shipping should the float end be faced beyond its normal movement in either direction, the connection will give and allow the float end to rotate about the pin 46 above the pivoted connections of the actuating rod 7 and upon release will automatically resume its normal straight line position.

The additional safety features of this device for controlling the operation of a pump for filling a tank or drawing a liquid therefrom are obvious. Should the pipe from the pump to the tank, in the first instance, leak badly or become broken the float will sink to its lower position and break the pump motor circuit and, in the second instance, upon a leak or break in the pipe from the tank to the pump, the level of the liquid in the tank will sink, allowing the float to travel to its lower limit and thereupon break the pump motor circuit.

It is also obvious that this device is also applicable to a gasometer by attaching the float end of the float arm to the movable bell of the gasometer and thereby disconnect the motor when the bell has reached its uppermost and lowermost limits of travel.

What I claim is: v

1. A float operated electric switch mechanism including an electricswitch having an actuating member adapted upon movement in one direction to open the switch and upon movement in the opposite direction to close the switch, an actuating rod attached to the switch actuating member, a guide about the lower end of the actuating rod, resilient means normally holding the actuating member and rod with the switch in closed position, a float bearing arm, a pivotal connection between the free 'end of the float arm and lower end of the rod on the under side of the guide, said float arm cut away about the pivot allowing the resilient rmeans to draw the pivotal connection within said guide to contact the arm and hold it at an obtuse angle in relation to the rod, said arm cut away portion on the side of the float "forming a shoulder adapted to coact with the guide to allow slight rotation of the arm without excessive movement being imparted to the rod, said arm between said shoulder and float cut away to allow an upward movement thereof to clear the guide whereby upon continued upward movement the arm is fulcrumed by contact of shoulder and guide and the pivotal connection is drawn downward until it limits the upward travel of the float and the continued movement of the rod in this direction imparted to the actuating member opens the switch.

2. A float operated electric switch mechanism including an electric switch having an actuating member adapted upon movement in one direction to open the switch and upon movement in the opposite direction to close the switch, an actuating rod attached to the switch actuating member, a guide about the lower end of the actuating rod, resilient means normally holding the actuating memher and rod with the switch in closed position, a float bearing arm, a pivotal connection between the free end of the float arm and lower end of the rod on the under side of the guide, said float arm cut away about the pivot allowing the resilient means to draw the pivotal connection within said guide to contact the arm and hold it at an obtuse angle in relation to the rod, said arm cut away portion on the side opposite the float forming a shoulder adapted to coact with the guide to allow slight rotation of the arm without excessive movement being imparted to the rod, said arm beyond said shoulder being cut away to allow a downward movement of the float, whereby upon continued downward movement of the float the arm is fulcrumed by contact of shoulder and guide and the pivotal connection is drawn downward untll it limits the downward travel of the float and the continued movement of the rod in this direction imparted to the actuating member opens the switch.

position, a guide through which the rod passes, the other end of the actuating rod attached to one end of an arm attached at its other end to a float, the attachment between the actuating armnnd float arm comprising a pivot connecting the arm to the rod and the body of the arm cut away on each side of the pivot to form shoulders adapted to engage the guide to contact the arm and hold it at an obtuse angle in relation to the arm and when both shoulders engage the guide to allow the rod to normally close the switch and when the arm is rotated about its pivot to engage either shoulder and allow slight rotation of the arm without operation of the switch and upon the movement being continued in the same direction, the rod is moved downward to open the switch and prevent further rotation of the arm in that direction.

Signed at Chicago, Illinois, this 20th day of January, 1928.

IRA E. MoCABE. 

